title: Purification and characterization of a new metallo-neutral protease for beer brewing from Bacillus amyloliquefaciens SYB-001.
abstract: The increased additive amount of adjuncts in the raw materials of Chinese beer requires the usage of protease to release more water-soluble proteins. Here, a metallo-neutral protease suited for brewing industry was purified from Bacillus amyloliquefaciens SYB-001. A 5.6-fold purification of the neutral protease was achieved with a 4-step procedure including ammonium sulfate precipitation, ion-exchange, hydrophobic interaction, and gel-filtration chromatography. The molecular mass of the enzyme was estimated to be 36.8 kDa. The protease was active and stable at a wide range of pH from 6.0-10.0 with an optimum at pH 7.0. The highest activity of the purified enzyme was found at 50 °C. The existence of manganese ion would specifically enhance the protease activity. Comparing with other commercial neutral proteases in China, adding the new neutral protease during mashing process would release more amino acids from wort such as aspartic acid, arginine, methione, and histidine, resulting in a better amino acid profile in wort. Moreover, the wort processed with the new neutral protease had a higher α-amino nitrogen concentration, which would ensure a vigorous yeast growth and better flavor. The study of the enzyme could lay a foundation for its industrial application and further research.
authors.affiliation: Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, Jiangsu, China.
authors.forename: Jinjing
authors.initials: J
authors.lastname: Wang
authors.forename: Ailan
authors.initials: A
authors.lastname: Xu
authors.forename: Yansong
authors.initials: Y
authors.lastname: Wan
authors.forename: Qi
authors.initials: Q
authors.lastname: Li
mesh_terms: D001407:Bacillus / Q000145:classification / Q000201:enzymology*; D001515:Beer / Q000032:analysis* / Q000382:microbiology*; D004789:Enzyme Activation; D004795:Enzyme Stability; D008670:Metals / Q000737:chemistry*; D010447:Peptide Hydrolases / Q000737:chemistry* / Q000302:isolation & purification*; D013045:Species Specificity
chemical_list: D008670:Metals; D010447:Peptide Hydrolases